Meteor Over the United Kingdom

Originally posted by abeverage
I think often a meteorite is mistaken for a comet.

I think you mean "a meteor is mistaken for a comet"! A meteorite is a meteoroid that has made it through the atmosphere and is
found on the ground.

You are right that meteors are misidentified as comets sometimes, although it's more common in my experience that they are mistaken for planes (on
fire/in the process of crashing), or fireworks.

Originally posted by abeverage
Although meteorites typically move quickly across the sky, if they are at the right angle they can skip across our atmosphere for several minutes!

"Several minutes" is a bit of an exaggeration. The slowest moving earthgrazing meteors won't be visible for more that around a minute in the most
extreme cases. There has certainly never been a confirmed case where a meteor has been visible for multiple minutes. If I recall, the record is 72
seconds, and is held by the Peekskill meteorite/fireball.

A man-made reentry however can be visible for multiple minutes, since objects in orbit are slower moving than natural meteoroids.

Actually I meant meteoroid, but it was before my morning coffee. I guess if I am to correct I should expect to be corrected. And yeah I said minutes
as it could have been a cluster... en.wikipedia.org...

Originally posted by abeverage
And yeah I said minutes as it could have been a cluster... en.wikipedia.org...

Granted, a cluster is a possibility, but events of this type are exceptionally rare.

Most meteoroids don't linger in orbit for a while before breaking up and entering the atmosphere. So I stand by what I said, despite this rare
exception.

Still, nice to see the meteor procession of 1913 brought up on ATS

I remember seeing the film of the 1972 Daylight Fireball as kid and it is still a lasting memory of how lucky we are! But also it peaked my curiosity
and help lead me into being an amateur astronomer who still makes amateur mistakes…

Originally posted by abeverage
I remember seeing the film of the 1972 Daylight Fireball as kid and it is still a lasting memory of how lucky we are! But also it peaked my curiosity
and help lead me into being an amateur astronomer who still makes amateur mistakes…

As we all do. I'm sure even pros make amateur mistakes from time to time.

I agree, we are lucky to live in an amazing universe. A night spent observing the
Leonid "fireball storm" of 1998 (by a stroke of pure luck - the
Leonid peak that year was forecast for the following night) is what first got me interested in astronomy, especially meteors/fireballs.

Originally posted by abeverage
Rare as it might be unless we get something official saying it was space junk what else would be seen for that long?

I'm not sure that there were any confirmed reports of the UK fireball lasting over a minute, although I did suggest that this may have been the case
earlier in the thread - but it's not uncommon for reported descriptions of events like this to be inaccurate. It's rare for people to be watching a
clock whilst observing a big meteor, and when adrenalin kicks in perceived timings can be way off.

The only way to be sure is to analyze the footage that is available, and thankfully there is a fair bit, so there is a good chance we will find
out.

I am still not so sure that it wasn't a satellite/junk reentry, despite the reasons mentioned earlier in this thread that make it less probable. To
that end, most of last night was spent stacking frames from fireball footage to try and get some star detail and work out a precise track of the
object in the sky, but to no avail alas. It's a bit of a long shot anyway.

I am slowly starting to think that the odds are tipping in favor of it being a normal very-slow natural fireball, perhaps even a rare cluster, but
it's less likely than the other two possibilities I think.

Originally posted by FireballStorm
The only way to be sure is to analyze the footage that is available, and thankfully there is a fair bit, so there is a good chance we will find
out.

I am still not so sure that it wasn't a satellite/junk reentry, despite the reasons mentioned earlier in this thread that make it less probable. To
that end, most of last night was spent stacking frames from fireball footage to try and get some star detail and work out a precise track of the
object in the sky, but to no avail alas. It's a bit of a long shot anyway.

I am slowly starting to think that the odds are tipping in favor of it being a normal very-slow natural fireball, perhaps even a rare cluster, but
it's less likely than the other two possibilities I think.

I would be curious to your findings. You are stacking to get more detail in the background? You use deepsky for this or something else?

Well we have the time, date and (do we have supposed direction?). Should be easy enough to throw into Stellarium if that is what you are planning to
do. I could verify for you if get some time. Other then that I am lousy at tracking or calculating orbits.

Originally posted by abeverage
Well we have the time, date and (do we have supposed direction?).

Apparently the camera was pointing WSW.

Originally posted by abeverage
Should be easy enough to throw into Stellarium if that is what you are planning to do..

I've just been using SkyMap Pro and comparing that side-by-side with the enhanced stacks.

Does Stellarium allow you to load up an image and then checks for matches itself? If so that would be very useful.

Originally posted by abeverage
I could verify for you if get some time.

If you could, that would be great!

Originally posted by abeverage
Other then that I am lousy at tracking or calculating orbits.

Me too, but we don't need to calculate orbits - just need to get a rough idea of the objects path in the sky in relation to the stars. I've outlined
how I intend to identify any possible satellites/junk in this thread here, and there
are some more examples here if you are interested.

I'm sure others are working on calculating orbits right now, if it has not been done already.

Let me start with the analysis result, since it's pretty exciting:
the UK bolide of 21 September 2012 was an earth-grazer: it's pre-
earth-encounter trajectory did NOT intersect the earth! It came
very close -- a minimum altitude of about 57 km over western Ireland.
Coincidentally, this is the same minimum altitude that was
achieved by the Grand Teton Daytime Fireball of 1972, although
that encounter lacked the significant fragmentation seen last
Friday.) Thanks to that fragmentation coupled with the low altitude,
some meteorites may have actually made it to the ground (or more
likely the ocean). But a significant fraction of the original
meteoroid went right back into space. Depending on the velocity
(which I would need a good video to estimate), the original
asteroid's orbit may have been sufficiently aerobraked to have
been captured by earth's gravity. If so, then the remaining fragments
would have reentered for good one orbit later in the middle of
the North Atlantic.

I know this is a bit of bad news as far as meteorite recovery, but
it's nevertheless an important result since it is one of the
extremely rare instances of an earth-grazing asteroid being not
only witnessed by hundreds if not thousands of people, but also
imaged by multiple cameras, both still and video.

1. Damien Stenson's beautiful image taken just south of O'Brien's
Tower on the Cliffs of Moher in County Clare, Ireland. At least
four bright fragments pass through the bowl of the Big Dipper,
behind the central tower and then disappear behind clouds low
in the west-northwest.

Early press coverage also suggested the event may have been a man-made re-entry. However, if we assume the average visible duration noted above
was roughly correct, and that the full visible path was between circa 500 to 1000 km long as a crude estimate, the object's velocity, not allowing for
deceleration, would have been well above any near-Earth man-made object's, but comfortably within the expected meteor atmospheric-entry range, between
~20 to 40 km/sec.

More on the 21 September 2012 fireball: why it definitely was a meteor

Observers report durations between 20-60 seconds: most video's on the web suggest a 40+ seconds duration.

It would take a reentering satellite travelling at 8 km/s (the orbital speed at decay altitudes) about 138 seconds or roughly 2.25 minutes to travel
this distance. While the reported fireball durations are long, none of the reports nor videos comes even remotely close to that value.

A meteoric fireball travelling at the lowest speed possible for such an object, 11.8 km/s, would take 93 seconds to travel that distance. This is
still longer than almost all of the reports suggest, but clearly getting closer.

If we take an estimated duration of 60 seconds, the 1100 km trajectory length results in a speed of approximately 18 km/s.

18 km/s is a very reasonable speed for a slow, asteroidal origin fireball.

(it is, let me repeat, also way too fast for a satellite reentry).

Meteorite dropping fireballs typically have speeds between 11.8 and 27 km/s. A speed near 18 km/s sits squarely in the middle of that speed
interval.

Edit to add graph:

He goes on to say:

Note 2: on how I made this quick and (emphasis) rough trajectory reconstruction. I took observations that contain clear sky locations: e.g. a sighting
from Dublin stating it went "through the pan of the Big Dipper"; the description from Bussloo observatory in the Netherlands; and later adding a.o. a
photo from Halifax, UK, showing it just above the tail of Ursa Major. These descriptions can be turned into directions and elevations. Next, I drew
lines from these sighting points towards the indicated directions, marking distances roughly corresponding to 30, 50 and 80 km altitude as indicated
by the observed elevation [ distance = altitude / tan(elevation) ]. Near the start of the trajectory I marked 50 and 80 km, for Britain and Ireland I
marked 30 and 50 km. These points then provide you with a rough trajectory.
From Dublin the object passed through North towards west. From Bussloo the object started NE (azimuth 60 degrees): these are important points of
information too as it shows that the object started at least as far east as the Dutch-German border (and more likely over Sleswig-Holstein in
N-Germany) and had its endpoint at least as far west as the northern part of Ireland.

[UPDATED] The 21 September fireball: a small Aten asteroid?

In my previous post I presented clear evidence that the splendid fireball seen over NW Europe on September 21st, 2012, was a meteoric fireball.
I also presented a first, very preliminary idea of its trajectory.

Based on that trajectory, I can now present some very first, very cautious conclusions about the heliocentric orbit of this
meteoroid.The solutions strongly favour an identification as an Aten asteroid.

The Aten asteroids are a group of near-Earth asteroids, named after the first of the group to be discovered (2062 Aten, discovered January 7,
1976, by Eleanor F. Helin). They are defined by having semi-major axes of less than one astronomical unit (the distance from the Earth to the Sun).
Because asteroids' orbits can be highly eccentric, an Aten orbit need not be entirely contained within Earth's orbit; in fact, nearly all known Aten
asteroids have their aphelion greater than one AU even though their semi-major axis is less than one AU. Observation of objects inferior to the
Earth's orbit is difficult and may be the cause of some bias in the apparent preponderance of eccentric Atens.

It is true, lots of people on ATS speculate from an inexperienced position... but not everyone here is inexperienced when it comes to this subject.

Originally posted by shenk
I don't recall "meteors" or "space-junks" having light dots around it and moving at such a slow speed

Weather you have come across such an event in the past or not, the fact remains that meteoroids do fragment, and there is plenty of evidence
for it being real.

For example the Peekskill meteor, which can clearly be seen to fragment.

Admittedly, the fragments in this case do not behave quite like those from the Peekskill fireball, but that is because the UK fireball was a very
unusual type of fireball!

Have you ever seen footage of a meteoroid that was temporarily captured by Earth's gravity causing a fireball before? If not, then why would
you expect to see what looks like footage from a more ordinary fireball???

Big Meteoroid Boomerangs Around Earth
For the first time ever, a meteor has grazed in and out of Earth's atmosphere, slowing enough to become a temporary satellite that perhaps lasted a
full orbit.

And because it was "slow", in your experience (which is obviously very limited in this particular field, or you would know that meteors can be slow,
especially in unusual cases like this one), it "can't have been one"?

Perhaps you should take your own advice:

Originally posted by shenk
Why do people speculate on things they don't understand is beyond my mind...

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